MERLIN for high luminosity large hadron collider collimation

The large hadron collider (LHC) uses the most energetic and highest luminosity man made proton beams on Earth. The high luminosity (HL-LHC) [1] upgrade aims to increase the levelled luminosity of the LHC by a factor of five, to 5 · 1034cm−2 s −1 , by increasing the bunch population from 1 to 2.22·1011 protons, and decreasing emittance, and β ∗ . Thus the stored beam energy increases from ≈ 362 MJ to ≈ 675 MJ per beam. All synchrotrons encounter unavoidable proton losses. Protons that populate the beam halo pose a threat to the performance and lifetime of certain hardware, such as superconducting magnets, which in the LHC may be quenched by an impact of ≈ 1 · 106 protons [2]. A multi stage collimation system must operate at an efficiency such that no more than 2 · 10−5% of protons incident on collimators may escape and impact upon these magnets [3]. To predict and protect against proton losses in the HL-LHC, collimation simulations must be performed. MERLIN, a C++ accelerator physics library, has been updated to carry out such simulations for the HL-LHC. Novel materials such as molybdenum graphite have been investigated as collimator materials, and a novel technique - collimation enhancement via a hollow electron lens (HEL) - has been studied. Using detailed simulations the performance and operation of possible collimation upgrades are explored.